The present invention relates to equipment for locating a current position of a mobile handset by using a radio signal.
JP-A-7-181242 discloses a method for calculating a present position of a mobile handset by using a signal of a cellular telephone. The method of locating the current position of a mobile handset as disclosed in this official gazette will be described below. The mobile handset receives signals transmitted from three cellular telephone base stations. Based on the received signals, the mobile handset calculates differences in propagation time among the signals from the three base stations. The mobile handset, using the propagation time differences, calculates the current position according to triangulation.